Ion Exchange Example Assessment

DOE-HDBK-3010-94

7.0 Application Examples; Liquid Storage and Ion Exchange Examples

The RF assessed for this correlation is 0.3, which yields a combined ARF x RF of

5E-2. As this value is less than the combined ARF x RF of 7E-2 assessed for less

extreme conditions, the 7E-2 value is used. Therefore, this calculation winds up

estimating the same source term as the previous calculation that used the bounding

ARF x RF for less than 100 oC superheat.

7.3.6.3

Ion Exchange Example Assessment

The bounding initial respirable source term estimated for the example configuration (i.e.,

Pyrex columns) is 65 g of plutonium, although this value could be as low as 10 g or less

depending on when in the process the exotherm occurred and what percentage of resin

actually burned. However, definitively specifying such parameters is not possible. It is

probably best to estimate how much the source term would be reduced by the building

leakpath factor before expending effort trying to reduce the source term by arguments such

as the ability of fire suppression systems/practices or explosive dispersion to minimize the

amount of resin that actually burns. In any case, the appropriate focus is on identifying

controls to prevent and/or mitigate the accident. What is being determined by the source

term calculation is the level of priority of those controls, not an absolute assurance that a

release will be below a given value if preventive and mitigative systems fail.

Now that a spectrum of source terms has been developed, the potential nonconservatism of

assuming a thermal explosion as opposed to a chemical detonation can be revisited. If a

detonation had been assumed as the release model, burning resin release and flashing spray

would not be significant factors due to the speed of the reaction and its energy, which would

disperse resin widely. The guidance in this handbook would estimate that a mass of inert

material equal to the TNT equivalent mass of the detonation would go airborne. In the case

of the ion exchange column, the inert mass includes both resin and liquid in the resin bed.

The mass of resin in a column is ~ 15,000 g. The previous resin void volume estimate of

50% is reduced by half to 25% in order to minimize the mass of liquid. The resulting

estimate of 5.8 l of liquid would add an additional 5800 g of inert material if the density of

water is assumed. Therefore, any one ion exchange column would contain ~ 20,800 g of

inert material in the region where the explosion would take place. If total plutonium loading

is distributed between two columns, a maximum of 3250 g of plutonium would be in any one

column, resulting in an overall grams plutonium to grams inert ratio of 0.16.

The bounding release for the actual example was 65 g of plutonium. If an exotherm in one

column leads to an exotherm in the second loaded column, the explosion of each column

would have to generate 32.5 g of airborne plutonium. By the ratio just calculated, 203 g of

total material would go airborne to generate 32.5 g of airborne plutonium. This would

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